Benchmarking of grid fault modes in single-phase grid-connected photovoltaic systems

Abstract

Pushed by the booming installations of single-phase photovoltaic (PV) systems, the grid demands regarding the integration of PV systems are expected to be modified. Hence, the future PV systems should become more active with functionalities of low voltage ride-through (LVRT) and the grid support capability. The control methods, together with grid synchronization techniques, are responsible for the generation of appropriate reference signals in order to handle ride-through grid faults. Thus, it is necessary to evaluate the behaviors of grid synchronization methods and control possibilities in single phase systems under grid faults. The intent of this paper is to present a benchmarking of grid fault modes that might come in future single-phase PV systems. In order to map future challenges, the relevant detection and control strategies are discussed. Some faulty modes are studied experimentally and provided at the end of this paper. It is concluded that there are extensive control possibilities in singlephase PV systems under grid faults. The Second Order General Integral based PLL technique might be the most promising candidate for future single-phase PV systems because of its fast adaptive-filtering characteristics and is able to full fill future standards.

Power quality improvement of single-phase photovoltaic systems through a robust synchronization method

“…The QSG used in the proposed synchronization is a combination of an IPT [6], [20]- [22], which can be considered as a band pass filter, and a T/4 delay transportation [19]- [20] as it is shown in Fig. 2.…”

“…In contrast, the Inverse Park Transform (IPT) based PLL method [20]- [22] can filter high frequency harmonics. Some interesting techniques based on adaptive filtering and generalized integrators, such as the enhanced PLL and a Second Order Generalized Integrator (SOGI) are presented in [19]- [20], [23]- [25], which present similar filtering response with IPT-PLL, where the low frequency harmonics are not eliminated. Finally, in [22], [26], a Hilbert based PLL technique is presented.…”

“…Phase-Locked Loop (PLL) algorithms have been widely used for the synchronization. Hence, PLL based synchronization methods in single-phase PV systems require further improvement as depicted in [15]- [19] in order to ensure a proper operation of the PV systems.…”

“…Then, this vector is transformed into the synchronous reference frame (v dq ), where a simple PI controller regulates the voltage v q to zero and therefore the phase angle is extracted [19]- [20]. In each PLL technique, a different Quadrature Signal Generator (QSG) is used to generate the vector v αβ .…”

“…In each PLL technique, a different Quadrature Signal Generator (QSG) is used to generate the vector v αβ . A straightforward T/4 delay transport technique is used in [6], [19]- [20] as a QSG, where T is the fundamental period of the grid voltage. Inaccuracy in the case of low or high order harmonics is the main drawback of this PLL system due to the lack of filtering.…”